1. Field of the Invention
The present invention relates to a handle apparatus for a manual motor starter, and more particularly to a handle apparatus of a manual motor starter, which has an improved structure for power transfer between a driving lever and a control lever of the starter, thereby minimizing the wear on parts of the starter and improving both the durability of the starter and the reliability in handle operation of the starter.
2. Description of the Prior Art
As is generally known in the art, a manual motor starter includes a detection part for detecting generation of accidental current, a switching mechanism operated when the generation of accidental current is detected, a contactors operated by the switching mechanism to switch on or off an electric path, an arc extinguishing mechanism for extinguishing and discharging an arc gas which may be generated when contactors are opened and a rotary handle 1 for manually operating the position of the starter to a ON position or OFF position.
FIG. 1 is a perspective view of a conventional manual motor starter for protecting a motor, which includes a manual motor starter body (hereinafter, referred to as “MMS body”) 100, a rotary handle 1 provided at the top of the MMS body 100, and an Under Voltage Trip (hereinafter, referred to as “UVT”) mechanism provided at one side of the MMS body 100.
When a user rotates the handle 1 to the ‘ON’ position in order to turn on the manual motor starter for starting a moter, the rotation of the handle 1 moves links of a switching mechanism in the MMS body 100, causing a movable contactor to come into contact with a stationary contactor, so that electrical current flow between the contactors. In contrast, when the user rotates the handle 1 to the ‘OFF’ position, the links move to separate the contactors from each other, thereby interrupting the flow of electricity. In the manual motor starter having the construction as described above, an apparatus for transferring the rotational displacement of the handle 1 to accessory devices is necessary.
The UVT mechanism is one of various accessory devices of a manual motor starter (hereinafter, referred to as “MMS”) from accidents such as short-circuiting or motor overloads. The UVT mechanism trips the switching mechanism in the MMS body 100 when an under voltage below a rated voltage is applied to the MMS.
FIG. 2 is a perspective view of a handle apparatus of a conventional MMS in a state where the MMS is turned off, and FIG. 3 is a perspective view of a handle apparatus of a conventional MMS in a state where the MMS is turned on.
As shown in FIGS. 2 and 3, a handle apparatus of a conventional MMS includes a handle 1 for interrupting turn-on of the MMS, an interlocking assembly 2 connected to the handle 1, a driving lever 3 operated by a driving gear 3a engaged with an interlocking gear 2a of the interlocking assembly 2, and a control lever 4 rotated about a control lever rotation shaft 5 by the driving lever 3.
The handle 1 can be rotated within an operation range between an “ON” operation and an “OFF” operation. The interlocking assembly 2 is rotated at the same angle as that of the handle 1 according to the rotation of the handle 1. The interlocking assembly 2 has the interlocking gear 2a which is engaged with the driving gear 3a of the driving lever 3 perpendicularly.
The driving lever 3 is rotated about a driving gear rotation shaft 3c according to the rotation of the interlocking assembly 2. Specifically, the driving lever 3 has the driving gear 3a formed at one side thereof, which is engaged with the interlocking gear 2a, so that the driving lever 3 can be rotated according to rotation of the driving gear 3a by the rotation of the interlocking assembly 2. The driving lever 3 also has a protrusion 3b formed at the other side of the driving lever 3.
The control lever 4 has a crank hole 4a formed through the control lever 4. The crank hole 4a has hole circumferences 4b formed at opposite ends of the crank hole 4a, through which the protrusion 3b of the driving lever 3 is inserted. Therefore, the control lever 4 can be rotated about the control lever rotation shaft 5 within a predetermined angular range by the rotation of the driving lever 3.
According to the rotation of the handle 1, the MMS performs an ‘ON’ operation for causing the switching mechanism to contact the movable contactor with the stationary contactor, thereby supplying current to a motor, or an ‘OFF ’operation for causing the switching mechanism to separate the movable contactor from the stationary contactor, thereby interrupting the supply of current to a motor.
The handle 1 is allowed to rotate within an angular range of 90° for the ‘ON’ and ‘OFF’ operations, and the control lever 4 connected to the handle 1 is allowed to rotate within an angular range of 47° for the ‘ON’ and ‘OFF’ operations.
In order to guarantee smooth operation of the control lever 4 following the operation of the handle 1, the control lever 4 has the crank hole 4a The protrusion 3b of the driving lever 3 is guided along the hole circumferences 4b of the crank hole 4a while preventing play of the control lever 4 in an unexpected direction, thereby achieving a smooth rotation of the control lever 4.
When the handle 1 of the MMS is at the OFF position as shown in FIG. 2, the protrusion 3b of the driving lever 3 is located at the upper end of the crank hole 4a of the control lever 4. While the handle 1 of the MMS is rotated to the ON position as shown in FIG. 3, the protrusion 3b of the driving lever 3 moves downward along the hole circumference 4b of the crank hole 4a and returns to its original position along the hole circumference 4b of the crank hole 4a. 
However, in the handle apparatus of the conventional MMS having the construction as described above, the protrusion 3b of the driving lever 3 made from synthetic resin is incontinuous contact with the hole circumferences 4b of the crank hole 4a of the control lever 4 made from metal while being moved by the rotation of the handle 1. Therefore, the protuberance 3b of the driving lever 3 made from synthetic resin may be easily worn out
Further, this problem (wearing of the protuberance 3b of the driving lever 3 made from synthetic resin) may become more severe when the handle 1 is operated by an increased driving power or at a higher speed.